Automated management of bundled applications

ABSTRACT

A new snapshot of a storage volume is created by instructing computing nodes to suppress write requests. Once pending write requests from the computing nodes are completed, storage nodes create a new snapshot for the storage volume by allocating a new segment to the new snapshot and finalizes and performs garbage collection with respect to segments allocated to the previous snapshot. An orchestration layer implements a bundled application that is provisioned with virtualized storage and computation resources. A snapshot of the bundled application may be created and used to rollback or clone the application. Clones snapshots of storage volumes may be gradually populated with data from prior snapshots to reduce loading on a primary snapshot. Chaos testing of the bundled application may be performed and storage volumes may be created, expanded, and/or moved based on usage of the bundled application.

RELATED APPLICATIONS

This application is related to U.S. application Ser. No. 16/167,049 filed Oct. 22, 2018, which is incorporated herein by reference for all purposes.

FIELD OF THE INVENTION

This invention relates to orchestration of roles in an application instantiated in a distributed storage and computation system.

BACKGROUND OF THE INVENTION

In many contexts, it is helpful to be able to return a database or distributed application to an original state or some intermediate state. In this manner, changes to the distributed application or other database configuration parameters may be tested without fear of corrupting critical data.

The systems and methods disclosed herein provide an improved approach for creating snapshots of a database and returning to a previous snapshot.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the advantages of the invention will be readily understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered limiting of its scope, the invention will be described and explained with additional specificity and detail through use of the accompanying drawings, in which:

FIG. 1 is a schematic block diagram of a network environment for implementing methods in accordance with an embodiment of the present invention;

FIG. 2 is a process flow diagram of a method for coordinating snapshot creation with compute nodes and storage nodes in accordance with an embodiment of the present invention;

FIG. 3 is a schematic diagram illustrating the storage of data within a storage node in accordance with an embodiment of the present invention;

FIG. 4 is a process flow diagram of a method for processing write requests in a storage node in accordance with an embodiment of the present invention;

FIG. 5 is a process flow diagram of a method for processing a snapshot instruction by a storage node in accordance with an embodiment of the present invention;

FIG. 6 is a process flow diagram of a method for performing garbage collection on segments in accordance with an embodiment of the present invention;

FIG. 7 is a process flow diagram of a method for reading data from a snapshot in accordance with an embodiment of the present invention;

FIG. 8 is a process flow diagram of a method for cloning a snapshot in accordance with an embodiment of the present invention;

FIG. 9 illustrates a snapshot hierarchy created in accordance with an embodiment of the present invention;

FIG. 10 is a process flow diagram of a method for rolling back to a prior snapshot in accordance with an embodiment of the present invention;

FIG. 11 illustrates the snapshot hierarchy of FIG. 9 as modified according to the method of FIG. 10 in accordance with an embodiment of the present invention;

FIG. 12 is a process flow diagram of a method for reading from a clone snapshot in accordance with an embodiment of the present invention;

FIG. 13 is a schematic block diagram of components for implementing orchestration of multi-role applications in accordance with an embodiment of the present invention;

FIG. 14 is a process flow diagram of a method for orchestrating the deployment of a multi-role application in accordance with an embodiment of the present invention;

FIG. 15 is a process flow diagram of a method for implementing provisioning constraints in accordance with an embodiment of the present invention;

FIG. 16 is a process flow diagram of a method for creating a snapshot of a multi-role application in accordance with an embodiment of the present invention;

FIG. 17 is a process flow diagram of a method for rolling back a multi-role application in accordance with an embodiment of the present invention;

FIG. 18 is a diagram illustrating the use of a layered file system to improve application portability in accordance with an embodiment of the present invention;

FIG. 19 is a process flow diagram of a method for creating and moving a portable application in accordance with an embodiment of the present invention;

FIG. 20 is a process flow diagram of a method for testing a distributed application in accordance with an embodiment of the present invention;

FIG. 21 is a schematic block diagram of components of a storage node in accordance with an embodiment of the present invention;

FIG. 22 is a process flow diagram of a method for assigning storage volumes to a disk of a storage node in accordance with an embodiment of the present invention;

FIG. 23 is a process flow diagram of a method for managing storage volumes of a bundled application in accordance with an embodiment of the present invention;

FIG. 24 is a schematic block diagram of data structures for managing a number of volumes per disk in accordance with an embodiment of the present invention;

FIG. 25 is a process flow diagram of a method for managing the number of volumes per disk in accordance with an embodiment of the present invention; and

FIG. 26 is a schematic block diagram of an example computing device suitable for implementing methods in accordance with embodiments of the invention.

DETAILED DESCRIPTION

Referring to FIG. 1, the methods disclosed herein may be performed using the illustrated network environment 100. The network environment 100 includes a storage manager 102 that coordinates the creation of snapshots of storage volumes and maintains records of where snapshots are stored within the network environment 100. In particular, the storage manager 102 may be connected by way of a network 104 to one or more storage nodes 106, each storage node having one or more storage devices 108, e.g. hard disk drives, flash memory, or other persistent or transitory memory. The network 104 may be a local area network (LAN), wide area network (WAN), or any other type of network including wired, fireless, fiber optic, or any other type of network connections.

One or more compute nodes 110 are also coupled to the network 104 and host user applications that generate read and write requests with respect to storage volumes managed by the storage manager 102 and stored within the memory devices 108 of the storage nodes 108.

The methods disclosed herein ascribe certain functions to the storage manager 102, storage nodes 106, and compute node 110. The methods disclosed herein are particularly useful for large scale deployment including large amounts of data distributed over many storage nodes 106 and accessed by many compute nodes 110. However, the methods disclosed herein may also be implemented using a single computer implementing the functions ascribed herein to some or all of the storage manager 102, storage nodes 106, and compute node 110.

Referring to FIG. 2, the illustrated method 200 may be performed in order to invoke the creation of a new snapshot. Other than a current snapshot, which is still subject to change, a snapshot captures the state of a storage volume at a moment in time and is not altered in response to subsequent writes to the storage volume.

The method 200 includes receiving, by the storage manager 102 a request to create a new snapshot for a storage volume. A storage volume as referred to herein may be a virtual storage volume that may divided into individual slices. For example, storage volumes as described herein may be 1 TB and be divided into 1 GB slices. In general, a slice and its snapshot are stored on a single storage node 106, whereas a storage volume may have the slices thereof stored by multiple storage nodes 106.

The request received at step 202 may be received from a human operator or generated automatically, such as according to backup scheduler executing on the storage manager 102 or some other computing device. The subsequent steps of the method 200 may be executed in response to receiving 202 the request

The method 200 may include transmitting 204 a quiesce instruction to all compute nodes 110 that are associated with the storage volume. For example, all compute nodes 110 that have pending write requests to the storage volume. In some embodiments, the storage manager 102 may store a mapping of compute nodes 110 to a particular storage volume used by the compute nodes 110. Accordingly, step 204 may include sending 204 the quiesce instruction to all of these compute nodes. Alternatively, the instruction may be transmitted 204 to all compute nodes 110 and include an identifier of the storage volume. The compute nodes 110 may then suppress any write instructions referencing that storage volume.

The quiesce instruction instructs the compute nodes 110 that receive it to suppress 206 transmitting write requests to the storage nodes 106 for the storage volume referenced by the quiesce instruction. The quiesce instruction may further cause the compute nodes 110 that receive it to report 208 to the storage manager 102 when no write requests are pending for that storage volume, i.e. all write requests issued to one or more storage nodes 106 and referencing slices of that storage volume have been acknowledged by the one or more storage nodes 106.

In response to receiving the report of step 208 from one or more compute nodes, e.g. all compute nodes that are mapped to the storage node that is the subject of the snapshot request of step 202, the storage manager 102 transmits 210 an instruction to the storage nodes 106 associated with the storage volume to create a new snapshot of that storage volume. Step 210 may further include transmitting 210 an instruction to the compute nodes 110 associated with the storage volume to commence issuing write commands to the storage nodes 106 associated with the storage volume. In some embodiments, the instruction of step 110 may include an identifier of the new snapshot. Accordingly, subsequent input/output operations (IOPs) transmitted 214 from the compute nodes may reference that snapshot identifier. Likewise, the storage node 106 may associate the snapshot identifier with data subsequently written to the storage volume, as described in greater detail below.

In response to receiving 210 the instruction to create a new snapshot, each storage node 106 finalizes 212 segments associated with the current snapshot, which may include performing garbage collection, as described in greater detail below. In addition, subsequent IOPs received by the storage node may also be processed 216 using the new snapshot as the current snapshot, as is also described in greater detail below.

Referring to FIG. 3, the method by which slices are allocated, reassigned, written to, and read from may be understood with respect to the illustrated data storage scheme. The data of the storage scheme may be stored in transitory or persistent memory of the storage node 106, such as in the storage devices 108.

For each logical volume, the storage manager 102 may store and maintain a volume map 300. For each slice in the logical volume, the volume map may include an entry including a node identifier 302 identifying the storage node 106 to which the slice is assigned and an offset 304 within the logical volume at which the slice begins. In some embodiments, slices are assigned both to a storage node 106 and a specific storage device hosted by the storage node 106. Accordingly, the entry may further include a disk identifier of the storage node 106 referencing the specific storage device to which the slice is assigned.

The remaining data structures of FIG. 3 are stored on each storage node 106. The storage node 106 may store a slice map 308. The slice map 308 may include entries including a local slice identifier 310 that uniquely identifies each slice of the storage node 106, e.g. each slice of each storage device hosted by the storage node 106. The entry may further include a volume identifier 312 that identifies the logical volume to which the local slice identifier 310 is assigned. The entry may further include the offset 304 within the logical volume of the slice of the logical volume assigned to the storage node 106.

In some embodiments, an entry in the slice map 308 is created for a slice of the logical volume only after a write request is received that references the offset 304 for that slice. This further supports the implementation of overprovisioning such that slices may be assigned to a storage node 106 in excess of its actual capacity since the slice is only tied up in the slice map 308 when it is actually used.

The storage node 106 may further store and maintain a segment map 314. The segment map 314 includes entries either including or corresponding to a particular physical segment identifier (PSID) 316. For example, the segment map 314 may be in an area of memory such that each address in that area corresponds to one PSID 316 such that the entry does not actually need to include the PSID 316. The entries of the segment map 314 may further include a slice identifier 310 that identifies a local slice of the storage node 106 to which the PSID 316 has been assigned. The entry may further include a virtual segment identifier (VSID) 318. As described in greater detail below, each time a segment is assigned to logical volume and a slice of a logical volume, it may be assigned a VSID 318 such that the VSIDs 318 increase in value monotonically in order of assignment. In this manner, the most recent PSID 316 assigned to a logical volume and slice of a logical volume may easily be determined by the magnitude of the VSIDs 318 mapped to the PSIDs 316. In some embodiments, VSIDs 318 are assigned in a monotonically increasing series for all segments assigned to volume ID 312. In other embodiments, each offset 304 and its corresponding slice ID 310 is assigned VSIDs separately, such that each slice ID 310 has its own corresponding series of monotonically increasing VSIDs 318 assigned to segments allocated to that slice ID 310.

The entries of the segment map 314 may further include a data offset 320 for the PSID 316 of that entry. As described in greater detail below, when data is written to a segment it may be written at a first open position from a first end of the segment. Accordingly, the data offset 320 may indicate the location of this first open position in the segment. The data offset 320 for a segment may therefore be updated each time data is written to the segment to indicate where the new first open position is.

The entries of the segment map 314 may further include a metadata offset 322. As described in detail below, for each write request written to a segment, a metadata entry may be stored in that segment at a first open position from a second end of the segment opposite the first end. Accordingly, the metadata offset 322 in an entry of the segment map 314 may indicate a location of this first open position of the segment corresponding to the entry.

Each PSID 316 corresponds to a physical segment 324 on a device hosted by the storage node 106. As shown, data payloads 326 from various write requests are written to the physical segment 324 starting from a first end (left) of the physical segment. The physical segment may further store index pages 328 such that index pages are written starting from a second end (right) of the physical segment 324.

Each index page 328 may include a header 330. The header 330 may be coded data that enables identification of a start of an index page 328. The entries of the index page 328 each correspond to one of the data payloads 326 and are written in the same order as the data payloads 326. Each entry may include a logical block address (LBA) 332. The LBA 332 indicates an offset within the logical volume to which the data payload corresponds. The LBA 332 may indicate an offset within a slice of the logical volume. For example, inasmuch as the PSID 316 is mapped to a slice ID 310 that is mapped to an offset 304 within a particular volume ID 312, maps 308 and 314, and an LBA 332 within the slice may be mapped to the corresponding offset 304 to obtain a fully resolved address within the logical volume.

In some embodiments, the entries of the index page 328 may further include a physical offset 334 of the data payload 326 corresponding to that entry. Alternatively or additionally, the entries of the index page 328 may include a size 336 of the data payload 326 corresponding to the entry. In this manner, the offset to the start of a data payload 326 for an entry may be obtained by adding up the sizes 336 of previously written entries in the index pages 328.

The metadata offset 322 may point to the last index page 328 (furthest from right in illustrated example) and may further point to the first open entry in the last index page 328. In this manner, for each write request, the metadata entry for that request may be written to the first open position in the last index page 328. If all of the index pages 328 are full, a new index page 328 may be created and stored at the first open position from the second end and the metadata for the write request may be added at the first open position in that index page 328.

The storage node 106 may further store and maintain a block map 338. A block map 338 may be maintained for each logical volume and/or for each slice offset of each logical volume, e.g. for each local slice ID 310 which is mapped to a slice offset and logical volume by slice map 308. The entries of the block map 338 map include entries corresponding to each LBA 332 within the logical volume or slice of the logical volume. The entries may include the LBA 332 itself or may be stored at a location within the block map corresponding to an LBA 332.

The entry for each LBA 332 may include the PSID 316 identifying the physical segment 324 to which a write request referencing that LBA was last written. In some embodiments, the entry for each LBA 332 may further indicate the physical offset 334 within that physical segment 324 to which the data for that LBA was written. Alternatively, the physical offset 324 may be obtained from the index pages 328 of that physical segment. As data is written to an LBA 332, the entry for that LBA 332 may be overwritten to indicate the physical segment 324 and physical offset 334 within that segment 324 to which the most recent data was written.

In embodiments implementing multiple snapshots for a volume and slice of a volume, the segment map 314 may additionally include a snapshot ID 340 identifying the snapshot to which the PSID 316 has been assigned. In particular, each time a segment is allocated to a volume and slice of a volume, the current snapshot identifier for that volume and slice of a volume will be included as the snapshot ID 340 for that PSID 316.

In response to an instruction to create a new snapshot for a volume and slice of a volume, the storage node 106 will store the new current snapshot identifier, e.g. increment the previously stored current snapshot ID 340, and subsequently allocated segments will include the current snapshot ID 340. PSIDs 316 that are not filled and are allocated to the previous snapshot ID 340 may no longer be written to. Instead, they may be finalized or subject to garbage collection (see FIGS. 5 and 6).

FIG. 4 illustrates a method 400 for executing write instructions by a storage node 106, such as write instructions received from an application executing on a compute node 110.

The method 400 includes receiving 402 a write request. The write request may include payload data, payload data size, and an LBA as well as fields such as a slice identifier, a volume identifier, and a snapshot identifier. Where a slice identifier is included, the LBA may be an offset within the slice, otherwise the LBA may be an address within the storage volume.

The method 400 may include evaluating 404 whether a PSID 316 is allocated to the snapshot referenced in the write request and whether the physical segment 324 corresponding to the PSID 316 (“the current segment”) has space for the payload data. In some embodiments, as write requests are performed with respect to a PSID 316, the amount of data written as data 326 and index pages 328 may be tracked, such as by way of the data offset 320 and metadata offset 322 pointers. Accordingly, if the amount of previously-written data 326 and the number of allocated index pages 328 plus the size of the payload data and its corresponding metadata entry exceeds the capacity of the current segment it may be determined to be full at step 404.

If the current segment is determined 404 to be full, the method 400 may include allocating 406 a new PSID 316 as the current PSID 316 and its corresponding physical segment 324 as the current segment for the snapshot referenced in the write request. In some embodiments, the status of PSIDs 316 of the physical storage devices 108 may be flagged in the segment map 314 as allocated or free as a result of allocation and garbage collection, which is discussed below. Accordingly, a free PSID 316 may be identified in the segment map 314 and flagged as allocated.

The segment map 314 may also be updated 408 to include a slice ID 310 and snapshot ID 340 mapping the current PSID 316 to the snapshot ID, volume ID 312, and offset 304 included in the write request. Upon allocation, the current PSID 316 may also be mapped to a VSID (virtual segment identifier) 318 that will be a number higher than previously VSIDs 318 such that the VSIDs increase monotonically, subject, of course, to the size limit of the field used to store the VSID 318. However, the size of the field may be sufficiently large that it is not limiting in most situations.

The method 400 may include writing 410 the payload data to the current segment. As described above, this may include writing 410 payload data 326 to the free location closest to the first end of the current segment.

The method 400 may further include writing 412 a metadata entry to the current segment. This may include writing the metadata entry (LBA, size) to the first free location closest to the second end of the current segment. Alternatively, this may include writing the metadata entry to the first free location in an index page 328 that has room for it or creating a new index page 328 located adjacent a previous index page 328. Steps 410, 412 may include updating one or more pointers or table that indicates an amount of space available in the physical segment, such as a pointer 320 to the first free address closest to the first end and a pointer 322 to the first free address closest to the second end, which may be the first free address before the last index page 328 and/or the first free address in the last index page. In particular, these pointers may be maintained as the data offset 320 and metadata offset in the segment map 314 for the current PSID 316.

The method 400 may further include updating 416 the block map 338 for the current snapshot. In particular, for each LBA 332 referenced in the write request, an entry in the block map 338 for that LBA 332 may be updated to reference the current PSID 316. A write request may write to a range of LBAs 332. Accordingly, the entry for each LBA 332 in that range may be updated to refer to the current PSID 316.

Updating the block map 338 may include evaluating 414 whether an entry for a given LBA 332 referenced in the write request already exists in the block map 338. If so, then that entry is overwritten 418 to refer to the current PSID 316. If not, an entry is updated 416 in the block map 318 that maps the LBA 332 to the current PSID 316. In this manner, the block map 338 only references LBAs 332 that are actually written to, which may be less than all of the LBAs 332 of a storage volume or slice. In other embodiments, the block map 338 is of fixed size and includes and entry for each LBA 332 regardless of whether it has been written to previously. The block map 338 may also be updated to include the physical offset 334 within the current segment to which the data 326 from the write request was written.

In some embodiments, the storage node 106 may execute multiple write requests in parallel for the same LBA 332. Accordingly, it is possible that a later write can complete first and update the block map 338 whereas a previous write request to the same LBA 332 completes later. The data of the previous write request is therefore stale and the block map 338 should not be updated.

Suppressing of updating the block map 338 may be achieved by using the VSIDs 318 and physical offset 334. When executing a write request for an LBA, the VSID 318 mapped to the segment 324 and the physical offset 334 to which the data is to be, or was, written may be compared to the VSID 318 and offset 334 corresponding to the entry in the block map 338 for the LBA 332. If the VSID 318 mapped in the segment map 314 to the PSID 316 in the entry of the block map 338 corresponding to the LBA 332, then the block map 338 will not be updated. Likewise, if the VSID 318 corresponding to the PSID 316 in the block map 338 is the same as the VSID 318 for the write request and the physical offset 334 in the block map 338 is higher than the offset 334 to which the data of the write request is to be or was written, the block map 338 will not be updated for the write request.

As a result of steps 414-418, the block map 338 only lists the PSID 316 where the valid data for a given LBA 332 is stored. Accordingly, only the index pages 328 of the physical segment 324 mapped to the PSID 316 listed in the block map 338 need be searched to find the data for a given LBA 332. In instances where the physical offset 334 is stored in the block map 338, no searching is required.

FIG. 5 illustrates a method 500 executed by a storage node 106 in response to the new snapshot instruction of step 210 for a storage volume. The method 500 may be executed in response to an explicit instruction to create a new snapshot or in response to a write request that includes a new snapshot ID 340. The method 500 may also be executed with respect to a current snapshot that is still being addressed by new write requests. For example, the method 500 may be executed periodically or be triggered based on usage.

The method 500 may include allocating 502 a new PSID 316 and its corresponding physical segment 324 as the current PSID 316 and current segment for the storage volume, e.g., by including a slice ID 310 corresponding to a volume ID 312 and offset 304 included in the new snapshot instruction or the write request referencing the new snapshot ID 340. Allocating 502 a new segment may include updating 504 an entry in the segment map 314 that maps the current PSID 316 to the snapshot ID 340 and a slice ID 310 corresponding to a volume ID 312 and offset 304 included in the new snapshot instruction.

As noted above, when a PSID 316 is allocated, the VSID 318 for that PSID 316 may be a number higher than all VSIDs 318 previously assigned to that volume ID 312, and possibly to that slice ID 310 (where slices have separate series of VSIDs 318). The snapshot ID 340 of the new snapshot may be included in the new snapshot instruction or the storage node 106 may simply assign a new snapshot ID that is the previous snapshot ID 340 plus one.

The method 500 may further include finalizing 506 and performing garbage collection with respect to PSIDs 316 mapped to one or more previous snapshots IDs 340 for the volume ID 312 in the segment map 314, e.g., PSIDs 316 assigned to the snapshot ID 340 that was the current snapshot immediately before the new snapshot instruction was received.

FIG. 6 illustrates a method 600 for finalizing and performing garbage collection with respect to segment IDs 340 for a snapshot (“the subject snapshot”), which may include the current snapshot or a previous snapshot. The method 600 may include marking 602 as valid latest-written data for an LBA 332 in the PSID 316 having the highest VSID 318 in the segment map 314 and to which data was written for that LBA 332. Marking 602 data as valid may include making an entry in a separate table that lists the location of valid data or entries for metadata in a given physical segment 324 or setting a flag in the metadata entries stored in the index pages 328 of a physical segment 324, e.g., a flag that indicates that the data referenced by that metadata is invalid or valid.

Note that the block map 338 records the PSID 316 for the latest version of the data written to a given LBA 332. Accordingly, any references to that LBA 332 in the physical segment 324 of a PSID 316 mapped to a lower-numbered VSID 318 may be marked 604 as invalid. For the physical segment 324 of the PSID 316 in the block map 338 for a given LBA 332, the last metadata entry for that LBA 332 may be found and marked as valid, i.e. the last entry referencing the LBA 332 in the index page 328 that is the last index page 328 including a reference to the LBA 332. Any other references to the LBA 332 in the physical segment 324 may be marked 604 as invalid. Note that the physical offset 334 for the LBA 332 may be included in the block map 334, so all metadata entries not corresponding to that physical offset 334 may be marked as invalid.

The method 600 may then include processing 606 each segment ID S of the PSIDs 316 mapped to the subject snapshot according to steps 608-620. In some embodiments, the processing of step 606 may exclude a current PSID 316, i.e. the last PSID 302 assigned to the subject snapshot. As described below, garbage collection may include writing valid data from a segment to a new segment. Accordingly, step 606 may commence with the PSID 316 having the lowest-valued VSID 318 for the subject snapshot. As any segments 324 are filled according to the garbage collection process, they may also be evaluated to be finalized or subject to garbage collection as described below.

The method 600 may include evaluating 608 whether garbage collection is needed for the segment ID S. This may include comparing the amount of valid data in the physical segment 324 for the segment ID S to a threshold. For example, if only 40% of the data stored in the physical segment 324 for the segment ID S has been marked valid, then garbage collection may be determined to be necessary. Other thresholds may be used, such as value between 30% and 80%. In other embodiments, the amount of valid data is compared to the size of the physical segment 324, e.g., the segment ID S is determined to need garbage collection if the amount of valid data is less than X % of the size of the physical segment 324, where X is a value between 30 and 80, such as 40.

If garbage collection is determined 608 not to be needed, the method 600 may include finalizing 610 the segment ID S. Finalizing may include flagging the segment ID S in the segment map 314 as full and no longer available to be written to. This flag may be stored in another table that lists finalized PSIDs 316.

If garbage collection is determined 608 to be needed, then the method 600 may include writing 612 the valid data to a new segment. For example, if the valid data may be written to a current PSID 316, i.e. the most-recently allocated PSID 316 for the subject snapshot, until its corresponding physical segment 324 full. If there is no room in the physical segment 324 for the current PSID 316, step 612 may include assigning a new PSID 316 as the current PSID 316 for the subject snapshot. The valid data, or remaining valid data, may then be written to the physical segment 324 corresponding to the current PSID 316 for the subject snapshot.

Note that writing 612 the valid data to the new segment maybe processed in the same manner as for any other write request (see FIG. 4) except that the snapshot ID used will be the snapshot ID 340 of the subject snapshot, which may not be the current snapshot ID. In particular, the manner in which the new PSID 316 is allocated to the subject snapshot may be performed in the same manner described above with respect to steps 406-48 of FIG. 4. Likewise, the manner in which the valid data is written to the current segment may be performed in the same manner as for steps 410-412 of FIG. 4. In some embodiments, writing of valid data to a new segment as part of garbage collection may also include updating the block map with the new location of the data for an LBA 332, such as according to steps 414-418 of FIG. 4. When the physical segment 324 of the current PSID 316 is found to be full, it may itself be subject to the process 600 by which it is finalized or subject to garbage collection.

After the valid data is written to a new segment, the method 600 may further include freeing 614 the PSID Sin the segment map 314, e.g., marking the entry in segment map 314 corresponding to PSID S as free.

The process of garbage collection may be simplified for PSIDs 316 that are associated with the subject snapshot in the segment map 314 but are not listed in the block map 338 with respect to any LBA 332. The physical segments 324 of such PSIDs 316 do not store any valid data. Entries for such PSIDs 316 in the segment map 314 may therefore simply be deleted and marked as free in the segment map 314

FIG. 7 illustrates a method 700 that may be executed by a storage node 106 in response to a read request. The read request may be received from an application executing on a compute node 110. The read request may include such information as a snapshot ID, volume ID (and/or slice ID), LBA, and size (e.g. number of 4 KB blocks to read).

The following steps of the method 700 may be initially executed using the snapshot ID 340 included in the read request as “the subject snapshot,” i.e., the snapshot that is currently being processed to search for requested data. The method 700 includes receiving 702 the read request by the storage node 106 and identifying 704 one or more PSIDs 316 in the segment map 314 assigned to the subject snapshot and searching 706 the metadata entries for these PSIDs 316 for references to the LBA 332 included in the read request.

The searching of step 706 may be performed in order of decreasing VSID 318, i.e. such that the metadata entries for the last allocated PSID 316 is searched first. In this manner, if reference to the LBA 332 is found, the metadata of any previously-allocated PSIDs 316 does not need to be searched.

Searching 706 the metadata for a PSID 316 may include searching one or more index pages 328 of the physical segment 324 corresponding to the PSID 316. As noted above, one or more index pages 328 are stored at the second end of the physical segment 324 and entries are added to the index pages 328 in the order they are received. Accordingly, the last-written metadata including the LBA 332 in the last index page 328 (furthest from the second end of the physical segment 324) in which the LBA 332 is found will correspond to the valid data for that LBA 332. To locate the data 326 corresponding to the last-written metadata for the LBA 332 in the physical segment 324, the sizes 336 for all previously-written metadata entries may be summed to find a start address in the physical segment 324 for the data 326. Alternatively, if the physical offset 334 is included, then the data 326 corresponding to the metadata may be located without summing the sizes 336.

If reference to the LBA 332 is found 708 in the physical segment 324 for any of the PSIDs 316 allocated to the subject snapshot, the data 326 corresponding to the last-written metadata entry including that LBA 332 in the physical segment 324 mapped to the PSID 316 having the highest VSID 318 of all PSIDs 316 in which the LBA is found will be returned 710 to the application that issued the read request.

If the LBA 332 is not found in the metadata entries for any of the PSIDs 316 mapped to subject snapshot, the method 700 may include evaluating 712 whether the subject snapshot is the earliest snapshot for the storage volume of the read request on the storage node 106. If so, then the data requested is not available to be read and the method 700 may include returning 714 a “data not found” message or otherwise indicating to the requesting application that the data is not available.

If an earlier snapshot than the subject snapshot is present for the storage volume on the storage node 106, e.g., there exists at least one PSID 316 mapped to a snapshot ID 340 that is lower than the snapshot ID 340 of the subject snapshot ID, then the immediately preceding snapshot ID 340 will be set 716 to be the subject snapshot and processing will continue at step 704, i.e. the PSIDs 316 mapped to the subject snapshot will be searched for the LBA 332 in the read request as described above.

The method 700 is particularly suited for reading data from snapshots other than the current snapshot that is currently being written to. In the case of a read request from the current snapshot, the block map 338 may map each LBA 332 to the PSID 316 in which the valid data for that LBA 332 is written. Accordingly, for such embodiments, step 704 may include retrieving the PSID 332 for the LBA 332 in the write request from the block map 338 and only searching 706 the metadata corresponding to that PSID 316. Where the block map 338 stores a physical offset 334, then the data is retrieved from that physical offset within the physical segment 314 of the PSID 336 mapped to the LBA 332 of the read request.

In some embodiments, the block map 332 may be generated for a snapshot other than the current snapshot in order to facilitate executing read requests, such as where a large number of read requests are anticipated in order to reduce latency. This may include searching the index pages 328 of the segments 324 allocated to the subject snapshot and its preceding snapshots to identify, for each LBA 332 to which data has been written, the PSID 316 having the highest VSID 318 of the PSIDs 316 having physical segments 324 storing data written to the each LBA 332. This PSID 316 may then be written to the block map 318 for the each LBA 332. Likewise, the physical offset 334 of the last-written data for that LBA 332 within the physical segment 324 for that PSID 316 may be identified as described above (e.g., as described above with respect to steps 704-716).

Referring to FIG. 8, in some instances it may be beneficial to clone a storage volume. This may include capturing a current state of a principal copy of a storage volume and making changes to it without affecting the principal copy of the storage volume. For purposes of this disclosure a “principal copy” or “principal snapshot” of a storage volume refers to an actual production copy that is part of a series of snapshots that is considered by the user to be the current, official, or most up-to-date copy of the storage volume. In contrast, a clone snapshot is a snapshot created for experimentation or evaluation but changes to it are not intended by the user to become part of the production copy of the storage volume. Stated differently, only one snapshot may be a principal snapshot with respect to an immediately preceding snapshot, independent of the purpose of the snapshot. Any other snapshots that are immediate descendants of the immediately preceding snapshot are clone snapshots.

The illustrated method 800 may be executed by the storage manager 102 and one or more storage nodes 106 in order to implement this functionality. The method 800 may include receiving 802 a clone instruction and executing the remaining steps of the method 800 in response to the clone instruction. The clone instruction may be received by the storage manager 102 from a user or be generated according to a script or other program executing on the storage manager 102 or a remote computing device in communication with the storage manager 102.

The method 800 may include recording 804 a clone branch in a snapshot tree. For example, referring to FIG. 9, in some embodiments, for each snapshot that is created for a storage volume, the storage manager 102 may create a node S1-S5 in a snapshot hierarchy 900. In response to a clone instruction, the storage manager 102 may create a clone snapshot and branch to a node A1 representing the clone snapshot. In the illustrated example, a clone instruction was received with respect to the snapshot of node S2. This resulted in the creation of clone snapshot represented by node A1 that branches from node S2. Note node S3 and its descendants are also connected to node S2 in the hierarchy.

In some embodiments, the clone instruction may specify which snapshot the clone snapshot is of In other embodiments, the clone instruction may be inferred to be a snapshot of a current snapshot. In such embodiments, a new principal snapshot may be created and become the current snapshot. The previous snapshot will then be finalized and be subject to garbage collection as described above. The clone will then branch from the previous snapshot. In the illustrated example, if node S2 represented the current snapshot, then a new snapshot represented by node S3 would be created. The snapshot of node S2 would then be finalized and subject to garbage collection and clone snapshot represented by A1 would be created and node A1 would be added to the hierarchy as a descendent of node S2.

In some embodiments, the clone node A1, and possibly its descendants A2 to A4 (representing subsequent snapshots of the clone snapshot), may be distinguished from the nodes S1 to S5 representing principal snapshots, such as by means of a flag, a classification of the connection between the node A1 and node S2 that is its immediate ancestor, or by storing data defining node A1 in a separate data structure.

Following creation of a clone snapshot, other principal snapshots of the storage volume may be created and added to represented in the hierarchy by one or more nodes S2 to S5. A clone may be created of any of these snapshots and represented by additional clone nodes. In the illustrated example, node B1 represents a clone snapshot of the snapshot represented by node S4. Subsequent snapshots of the clone snapshot are represented by nodes B1 to B3.

Referring again to FIG. 8, the creation of a clone snapshot on the storage node 106 may be performed in the identical manner as for any other snapshot, such as according to the methods of FIGS. 2 through 6. In particular, one or more segments 806 may be allocated to the clone snapshot on storage nodes 106 storing slices of the cloned storage volume and mapped to the clone snapshot. IOPs referencing the clone snapshot may be executed 808, such as according to the method 400 of FIG. 4.

In some instances, it may be desirable to store a clone snapshot on a different storage node 106 than the principal snapshots. Accordingly, the method 800 may include allocating 806 segments to the clone snapshot on the different storage node 106. This may be invoked by sending a new snapshot instruction referencing the clone snapshot (i.e., an identifier of the clone snapshot) to the different storage node 106 and instructing one or more compute nodes 110 to route IOPs for the clone snapshot to the different storage node 106.

The storage node 102 may store in each node of the hierarchy, data identifying one or more storage nodes 106 that store data for the snapshot represented by that node of the hierarchy. For example, each node may store or have associated therewith one or more identifiers of storage nodes 106 that store a particular snapshot ID for a particular volume ID. The node may further map one or more slice IDs (e.g., slice offsets) of a storage volume to one storage nodes 106 storing data for that slice ID and the snapshots for that slice ID.

Referring to FIG. 10, one of the benefits of snapshots is the ability to capture the state of a storage volume such that it can be restored at a later time. FIG. 10 illustrates a method 1000 for rolling back a storage volume to a previous snapshot, particularly for a storage volume having one or more clone snapshots.

The method 1000 includes receiving 1002, by the storage manager 102, an instruction to rollback a storage volume to a particular snapshot SN. The method 1000 may then include processing 1004 each snapshot that is a represented by a descendent node of the node representing snapshot SN in the snapshot hierarchy, i.e. snapshots SN+1 to SMAX, where SMAX is the last principal snapshot that is a descendent of snapshot SN (each “descendent snapshot”). For each descendent snapshot, processing 1004 may include evaluating 1006 whether the each descendent is an ancestor of a node representing a clone snapshot. If not, then the storage manager 102 may instruct all storage nodes 106 storing segments mapped to the descendent snapshot to free 1008 these segments, i.e. delete entries from the segment map referencing the descendent snapshot and marking corresponding PSIDs 316 as free in the segment map 314.

If the descendent snapshot is found 1006 to be an ancestor of a clone snapshot, then step 1008 is not performed and the snapshot and any segments allocated to it are retained.

FIG. 11 illustrates the snapshot hierarchy following execution of the method 1000 with respect to the snapshot represented by node S3. As is apparent, snapshot S5 has been removed from the hierarchy and any segments corresponding to these snapshots will have been freed on one or more storage nodes 106.

However, since node S4 is an ancestor of clone node B1, it is not removed and segments corresponding to it are not freed on one or more storage nodes in response to the roll back instruction. Inasmuch as each snapshot contains only data written to the storage volume after it was created, previous snapshots may be required to recreate the storage volume. Accordingly, the snapshots of nodes S3 to S1 are needed to create the snapshot of the storage volume corresponding to node B1.

Subsequent principal snapshots of the storage volume will be added as descendants of the node to which the storage volume was rolled back. In the illustrated example, a new principal snapshot is represented by node S6 that is an immediate descendent of node S3. Node S4 is only present due to clone node B1 and therefore may itself be classified as a clone node in the hierarchy in response to the rollback instruction of step 1002.

Note that FIG. 11 is a simple representation of a hierarchy. There could be any number of clone snapshots, clones of clone snapshots and descendent snapshots of any of these snapshots represented by nodes of a hierarchy. Accordingly, to roll back to a particular snapshot of a clone, the method 1000 is the same, except that descendants of the clone snapshot are treated the same as principal snapshots and clones of any of these descendants are treated the same as a clone snapshot.

Referring to FIG. 12, the illustrated method 1200 may be used to execute a read request with respect to a storage volume that is represented by a hierarchy generated as described above with respect to FIGS. 8 through 11. The illustrated method 1200 may also be executed with respect to a storage volume that includes only principal snapshots that are distributed across multiple storage nodes, i.e., all the segments corresponding to snapshots of the same slice of the storage volume are not located on the same storage node 106. In that case, the hierarchy stored on the storage manager 102 stores the location of the segments for each snapshot and therefore enables them to be located.

The method 1200 may be executed by a storage node 106 (“the current storage node”) with information retrieved from the storage manager 102 as noted below. The method 1200 may include receiving 1202 a read request, which may include such information as a snapshot ID, volume ID (and/or slice ID), LBA, and size (e.g. number of 4 KB blocks to read).

Note that the read request may be issued by an application executing on a compute node 110. The compute node 110 may determine which storage node 106 to transmit the read request using information from the storage manager 102. For example, the compute node 110 may transmit a request to obtain an identifier for the storage node 102 storing data for a particular slice and snapshot of a storage volume. The storage manager may then obtain an identifier and/or address for the storage node 106 storing that snapshot and slice of the storage volume from the hierarchical representation of the storage volume and return it to the requesting compute node 110. For example, the storage manager 102 may retrieve this information from the node in the hierarchy representing the snapshot included in the read request.

In response to the read request, the current storage node performs the algorithm illustrated by subsequent steps of the method 1200. In particular, the method 1200 may include identifying 1204 segments assigned to the snapshot ID of the read request in the segment (“the subject snapshot”).

The method 1200 may include searching 1206 the metadata of the segments identified in step 1204 for the LBA of the read request. If the LBA is found, the data from the highest numbered segment having the LBA in its metadata is returned, i.e. the data that corresponds to the last-written metadata entry including the LBA.

If the LBA is not found in any of the segments mapped to subject snapshot, then the method 1200 may include evaluating 1212 whether the subject snapshot is the earliest snapshot on the current storage node. If not, then steps processing continues at step 1204 with the previous snapshot set 1214 as the subject snapshot.

Steps 1204-1214 may be performed in the same manner as for steps 704-714 of the method 700, including the various modifications and variations described above with respect to the method 700.

In contrast to the method 700, if the LBA is not found in any of the segments corresponding to the subject snapshot for any of the snapshots evaluated, then the method 1200 may include requesting 1216 a location, e.g. storage node identifier, where an earlier snapshot for the volume ID or slice ID is stored. In response to this request, the storage manager 102 determines an identifier of a storage node 106 storing the snapshot corresponding to the immediate ancestor of the earliest snapshot stored on the current storage node in the hierarchy. The storage manager 102 may determine an identifier of the storage node 106 relating to the immediate-ancestor snapshot and that stores data for a slice ID and volume ID of the read request as recorded for the ancestor nearest ancestor node in the hierarchy of the node corresponding to the earliest snapshot stored on the current storage node.

If the current storage node is found 1218 to be the earliest snapshot for the storage volume ID and/or slice ID of the read request, then the data the storage manager 102 may report this fact to the storage node, which will then return 1220 a message indicating that the requested LBA is not available for reading, such as in the same manner as step 714 of the method 700.

If another storage node stores an earlier snapshot for the volume ID and/or slice ID of the read request, then the read request may be transmitted 1222 to this next storage node by either the current storage node or the storage manager 102. The processing may then continue at step 1202 with the next storage node as the current storage node. The read request transmitted at step 1222 may have a snapshot ID set to the latest snapshot ID for the storage volume ID and or slice ID of the original read request.

The method 1200 may be performed repeatedly across multiple storage nodes 106 until the earliest snapshot is encountered or the LBA of the read request is located.

Referring to FIG. 13, storage according to the above-described methods and systems may be incorporated into an application-orchestration approach. In the illustrates approach, an orchestration layer 1300 implements a bundled application 1302 including a plurality of roles. In the following description, “bundled application” refers to a bundle of applications as implemented using the orchestration layer. A “role” is an instance of an executable that is managed by the orchestration layer as described herein as part of the bundled application. Accordingly, a “role” may itself be a standalone application, such as a database, webserver, blogging application, or any other application. Examples of roles include the roles used to implement multi-role applications such as CASSANDRA, HADOOP, SPARK, DRUID, SQL database, ORACLE database, MONGODB database, WORDPRESS, and the like. For example, in HADOOP, roles may include one or more of a name node, data node, zookeeper, and AMBARI server.

The orchestration layer 1300 may implement a bundled application 1302 defining roles and relationships between roles as described in greater detail below. The orchestration layer 1300 may execute on a computing device of a distributed computing system (see e.g., FIG. 1), such as on a compute node 110, storage node 106, a computing device executing the functions of the storage manager 102, or some other computing device. Accordingly, actions performed by the orchestration layer 1300 may be interpreted as being performed by the computing device executing the orchestration layer 1300.

The bundled application 1302 may include a manifest 1304 that defines the roles of the bundled application 1302, which may include identifiers of roles and possibly a number of instances for each role identified. The manifest 1304 may define dynamic functions define how the number of instances of particular role may grow or shrink depending on usage. The orchestration layer 1300 may then create or remove instances for a role as described below as indicated by usage and one or more functions for that role. The manifest 1304 may define a topology of the bundled application 1302, i.e. the relationship between roles, such as services of a role that are accessed by another role.

The bundled application 1302 may include provisioning 1306. The provisioning 1306 defines the resources of storage nodes 106 and compute nodes 110 required to implement the bundle. The provisioning 1306 may define resources for the bundle as a whole or for individual roles. Resources may include a number of processors (e.g., processing cores), an amount of memory (e.g., RAM (random access memory), an amount of storage (e.g., GB (gigabytes) on a HDD (Hard Disk Drive) or SSD (Solid State Drive)). As described below, these resources may be provisioned in a virtualized manner such that the bundled application 1302 and individual roles 1312 are not informed of the actual location or processing and storage resources and are relieved from any responsibility for managing such resources. In particular, storage resources may be virtualized by the storage manager 102 using the methods described above such that storage volumes are allocated and used without requiring the bundled application 1302 or roles to manage the underlying storage nodes 106 and storage device 108 on which the data of the storage volumes is written.

Provisioning 1306 may include static specification of resources and may also include dynamic provisioning functions that will invoke allocation of resources in response to usage of the bundled application. For example, as a database fills up, additional storage volumes may be allocated. As usage of a bundled application increases, additional processing cores and memory may be allocated to reduce latency.

A bundled application 1302 may further include configuration parameters 1308. Configuration parameters may include variables and settings for each role of the bundle. The configuration parameters are defined by the developer of the role and therefore may include any example of such parameters for any application known in the art. The configuration parameters may be dynamic or static. For example, some parameters may be dependent on resources such as an amount of memory, processing cores, or storage. Accordingly, these parameters may be defined as a function of these resources. The orchestration layer will then update such parameters according to the function in response to changes in provisioning of those resources that are inputs to the function. For example, CASSANDRA defines a variable Max_Heap_Size that is normally set to half the memory limit. Accordingly, as the memory provisioned for a CASSANDRA role increases, the value of Max_Heap_Size may be increased to half the increased memory.

The bundled application 1302 may further include action hooks 1310 for various actions that may be taken with respect to the bundled application and/or particular roles of the bundled applications. Actions may include some or all of stopping, starting, restarting, taking snapshots, cloning, and rolling back to a prior snapshot. For each action, one or more action hooks may be defined. A hook is a programmable routine that is executed by the orchestration layer when the corresponding action is invoked. A hook may specify a script of commands or configuration parameters input to one or more roles in a particular order. Hooks for an action may include a pre-action hook (executed prior to implementing an action), an action hook (executed to actually implement the action), and a post action hook (executed following implementation of the action).

The bundled application 1302 may define a plurality of roles 1312. Each role may include one or more provisioning constraints. As noted above, the bundled application 1302 and roles 1312 are not aware of the underlying storage nodes 106 and compute nodes 110 inasmuch as these are virtualized by the storage manager 102 and orchestration layer 1300. Accordingly, any constraints on allocation of hardware resources may be included in the provisioning constraints 1314. As described in greater detail below, this may include constraints to create separate fault domains in order to implement redundancy and constraints on latency.

The role 1312 may define a name space 1316. A name space 1316 may include variables, functions, services, and the like implemented by a role. In particular, interfaces and services exposed by a role may be included in the name space. The name space may be referenced through the orchestration layer 1300 by an addressing scheme, e.g. <Bundle ID>.<Role ID>.<Name>. In some embodiments, references to the namespace 1316 of another role may be formatted and processed according to the JINJA template engine or some other syntax. Accordingly, each role 1312 may access the variables, functions, services, etc. in the name space 1316 of another role 1312 on order to implement a complex application topology. In some instances, credentials for authorizing access to a role 1312 may be shared by accessing the namespace 1316 of that role.

A role 1312 may further include various configuration parameters 1318 defined by the role, i.e. as defined by the developer that created the executable for the role. As noted above, these parameters 1318 may be set by the orchestration layer 1300 according to the static or dynamic configuration parameters 1308. Configuration parameters may also be referenced in the name space 1316 and be accessible (for reading and/or writing) by other roles 1312.

Each role 1312 may include a container 1320 executing an instance 1322 of the application for that role. The container 1320 may be a virtualization container, such as a virtual machine, that defines a context within which the application instance 1322 executes, facilitating starting, stopping, restarting, and other management of the execution of the application instance 1322. Containers 1320 may include any container technology known in the art such as DOCKER, LXC, LCS, KVM, or the like. In a particular bundled application 1302, there may be containers 1320 of multiple different types in order to take advantage of a particular container's capabilities to execute a particular role 1312. For example, one role 1312 of a bundled application 1302 may execute a DOCKER container 1320 and another role 1312 of the same bundled application 1302 may execute an LCS container 1320.

Note that a bundled application 1302 as configured in the foregoing description may be instantiated and used or may be saved as a template that can be used and modified later.

FIG. 14 illustrates a method 1400 for executing a bundled application 1302 using the orchestration layer 1300. The method 1400 may include provisioning 1402 storage and computation resources according to the provisioning 1306. This may include allocating storage volumes according to the storage requirements, assigning the storage volumes to storage nodes 106, and selecting a compute node 110 or storage node 106 providing the required computational resources (processor cores and memory).

The method 1400 may include creating 1404 role instances for the roles 1312 defined by the bundled application 1302. As described above, this may include creating a container 1320 and instantiating the application instance 1322 of the role 1312 within the container 1320. The order in which instances 1322 are created and started may be defined in the manifest 1304.

The method 1400 may include configuring 1406 each role according to the configuration parameters 1308, including executing any included functions to determine values for dynamic parameters. As noted above, starting a bundled application 1302 may further include setting up 1408 the roles 1312 to reference resources in the name space 1316 of another role 1312. For example, a webserver may be configured to access a database by referencing configuration parameters and services implemented by the database.

The method 1400 may further include executing 1410 any hooks 1310 defined for the initial startup of the bundled applications. Accordingly, pre-startup, startup, and post startup hooks may be executed. Some or all of the functions of steps 1402-1410 may be defined as part of the pre-startup hook. Other functions may also be performed prior to steps 1402-1408 as defined by a pre-startup hook.

The actual commencement of execution of the instances 1322 of the bundled application 1302 may be performed in an order specified by the startup hook and may include performing any attendant functions of these instances 1322 as specified by the startup hook. Following startup, one or more other actions may be performed as specified by the developer in the post-startup hook. These actions may invoke functions of the instances 1322 themselves or executed by the orchestration layer 1300 outside of the instances 1322, such as with respect to an operating system executing the containers 1320 for the instances 1322.

The bundled application 1302 may then be accessed 1412 in order to perform the programmed functionality of the application instances 1322. As usage occurs, processing resources will be loaded and storage may be filled. The method 1400 may further include adjusting 1414 provisioning according to this usage and may performed adjustment to configuration parameters of the roles 1312 according to this provisioning as defined by the provisioning 1306 and configuration functions 1308.

As noted above, instances of roles may also be created or removed according to usage. Accordingly, where indicate by the manifest 1304, instances 1322 for a role 1312 may be created according to steps 1402-1410 throughout execution of the bundled application 1302 as defined by one or more dynamic functions in the manifest 1304 for that role 1312.

Referring to FIG. 15, the illustrated method 1500 may be used to implement provisioning constraints 1314 for a role 1312 or constraints for an entire bundled application 1302. The method 1500 may be executed by the orchestration layer 1300, storage manager 102, or a combination of the two.

The method 1500 may include receiving 1502 the provisioning constraint 1314 for one or more roles 1312 of the bundled application 1302 and determining 1504 whether the constraint 1314 specify one or both of a fault domain constraint and a latency constraint.

If a latency constraint is found 1506 to be included for a role 1312, then computational resources and storage resources to be provisioned for the role 1312 may be constrained 1508 to be co-located. In particular, latency may be specified in terms of (a) a minimum network delay, (b) a minimum network throughput, (c) an explicit constraint to place computation and storage resources in the same subnetwork, or (d) an explicit constraint to place computation and storage resources on the same node, i.e. a hybrid compute and storage node 110, 106 that performs the functions of both types of nodes with a single computer.

This constraint may be used by the orchestration layer to assign computing and storage resources to roles 1312 and storage volumes of the bundled application. For example, one or more storage volumes for the role 1312 will be assigned to storage nodes 106 that can either (a) meet the latency requirement with respect to compute nodes 110 allocated to the role 1312 (b) also provide the computational resources required for the role 1312.

The orchestration layer 1300 may include a resource manager in that accounts for all of the compute storage requirements and constraints and creates a resource allocation plan. This plan describes the virtual nodes (containers 1320) that make up the bundled application 1302. Each virtual node has allocations of processor cores, memory and storage volumes. The resource manager determines the compute host (compute node 110 or hybrid node) for each virtual node and a set of devices for each storage volume of the virtual node. The orchestration layer 1300 sends this mapping of the storage volumes to physical devices to the storage manager 102, which implements the storage allocation.

If the constraint for a role 1312 is found 1510 to include a fault domain constraint, then storage volumes for the role 1312 may be distributed 1512 among the storage nodes 106 of the distributed storage system 100 according to this requirement. For example, if storage volume B is a redundant (e.g., replica or backup copy) of storage volume A, the fault domain constraint may indicate this fact. Accordingly, the storage manager 102 may assign storage volume B to a different storage node 106 than storage volume A. Various degrees of constraint may be specified. For example, a fault domain constraint may simply require a different storage device 108 but not require a different storage node 106. A fault domain constraint may require that storage nodes 106 to which storage volumes are assigned by in separate subnetworks, different geographic locations, or have some other degree of separation. Similar fault domain constraints may be specified for roles 1312, which may be constrained to execute on different compute nodes 110 in order to provide redundant services and reduce downtime.

The provisioning constraints 1502 based on fault domains and/or latency may be combined with one or more other constraints. For example, a performance constraint (IOPs/second) for a storage node may be imposed. Accordingly, only those compute nodes meeting the performance requirement and the fault domain and/or latency requirements will be selected for provisioning.

As noted above, provisioning 1306 may define a processing requirement, such as a number of processing cores and an amount of storage for a role. Accordingly, compute nodes 110 may be selected at step 1508 such that both the latency requirement and processing requirement are met.

Referring to FIG. 16, the illustrated method 1600 may be executed by the orchestration layer 1302 with respect to a bundled application 1302 in order to create a snapshot of the bundled application 1302 that can be later restored (see the method 1700 of FIG. 17).

The method 1600 may include flushing 1602 application buffers to disk. In many instances, performance of an application is accelerated by maintaining data in a cache in memory, such that data in the cache is accessed and updated without requiring writing to a disk in many instances, as known in the art. Accordingly, this buffer may be flushed 1602 to disk by writing all valid data (i.e., not outdated due to a subsequent write) in the cache to the storage device 108 to which that data is addressed, e.g., to which the storage volume referenced by the data is assigned.

In a like manner, a file system flush may be performed 1604. Performing a file system flush may include ensuring that all IOPs pending to be performed by the file system have been executed, i.e. written to disk. As for step 1602, data written to a cache for the file system this is valid may be written to a storage device 108 to which the data is addressed, e.g., to which the storage volume referenced by the data is assigned.

The method 1600 may then include freezing 1606 the application instances 1322 of each role 1312. In particular, inasmuch as each instance 1322 is executing within container 1320, the containers 1320 for the roles 1312 may be instructed to pause execution of each instance 1322. This may include stopping execution and saving a state of execution of each instance 1322 (state variables, register contents, program pointers, function stack, etc.).

The method 1600 may further include creating 1608 a snapshot of storage volumes provisioned for the bundled application. This may include executing the method 200 of FIG. 2 or any of the above-described approaches for implementing a snapshot of a storage volume.

The method 1600 may further include creating 1610 a topology snapshot for the bundled application 1302. The topology of an application may include some or all of the following information as constituted at the time of executing step 1610 a listing of the roles 1312, which may include one or more instances 1322 of the same role 1322, relationships between application instances 1322 of roles 1312 (name space cross-references, configuration parameters), storage volumes assigned to roles 1312, or other information that describes the topology of the bundled application 1302. Applications may create metadata describing their state of operation. This data may also be saved as part of the topology snapshot.

After the snapshot is created according to the method 1600, the application instances may be resumed, with the application itself not suffering any down time in some embodiments. The bundled application 1302 may then continue to operate. If desired, the application may then be rolled back to the snapshot created according to the method 1600, as described below with respect to FIG. 17.

FIG. 17 illustrates a method 1700 for rolling back a bundled application 1302 to a snapshot, such as a snapshot created according to the method 1600. The method 1700 may be executed by one or both of the orchestration layer 1300 and the storage manager 102.

The method 1700 includes receiving 1702 a rollback instruction, such as from an administrator desiring to return to a stable version of the bundled application 1302. The remaining steps of the method 1300 may be executed in response to the rollback instruction.

The method 1700 may include rolling 1704 back storage volumes assigned to the bundled application 1302 to the snapshots created for the snapshot of the bundled application 1302 (e.g., at step 1608 of the method 1600). This may include executing the method 1000 of FIG. 10 or performing any other approach for rolling back a storage volume to a prior state.

The method 1700 may include restoring 1706 application instances from the application snapshot. As described above with respect to step 1606 of the method 1600, an application instance 1322 may be frozen. Accordingly, data describing a state of execution of the application instance 1322 may be reloaded into a container 1302 for that instance. If needed, the container for that application instance 1322 may be created and the instance 1322 loaded into it prior to loading the state of execution. This is particularly the case where the number of application instances has changed since the application snapshot was created.

The method 1700 may further include restoring 1708 the application topology saved for the bundled application at step 1610. Accordingly, relationships between application instances 1322 of roles 1312 (name space cross-references, configuration parameters), storage volumes assigned to roles 1312, or other information that describes the topology of the bundled application 1302 may be restored as it was at the time the application snapshot was created

The method 1700 further include executing 1710, 1712, 1714 a pre-restart hook, restart hook, and post restart hook defined for the bundled application. As described above, each hook may be a routine defined by a developer to be executed for a particular action, restarting in this case. In step 1712, execution of the instances 1322 for the roles 1322 may be restarted, along with any other actions specified by the developer in the restart hook.

The bundled application 1302 as restored at steps 1704-1714 may then be accessed 1716 as defined by the programming of the application instances and the restored application topology.

Note that the snapshot of the bundled application 1302 may be restarted on different storage and compute nodes 106, 110 than those on which the bundled application 1302 was executing when the snapshot was created. Accordingly, the application snapshot may be restarted as a clone of the bundled application 1302 or moved to different hardware when executing the method 1700.

In some instances, the hooks of steps 1710, 1712, 1714 may be different when the application snapshot is being restarted as a clone as desired by a developer. For example, a developer may desire to scale the clone application to increase or decrease a number of databases, number of partitions of a database, or other aspect of the clone application. Accordingly, the hooks of steps 1710, 1712, 1714 may implement routines to implement this increase or decrease.

For example, some applications are able to automatically detect the number of partitions of a database. In such instances, some or all of the hooks 1710, 1712, 1714 may reduce the number of partitions in a database of the clone applications and rely on the application to discover this change. In other instances, some or all of the hooks 1710, 1712, 1714 may be programmed to configure an application to access the database with the reduced number of partitions where the application is unable to configure itself.

Referring to FIG. 18, as noted above, containers 1320 may be implemented as DOCKER containers. However, DOCKER containers are not particularly suited for implementing stateful applications in which some or all of the state of an application is stored in persistent storage. This may be a disadvantage, particularly where a snapshot of an application is to be create and used for rolling back or cloning (see discussion of FIG. 17).

In the illustrated approach, a DOCKER container 1320 is modified to use an external graph driver plugin for storing persistent data. In the illustrated embodiment, the graph driver plugin implements a layered file system 1800. In the illustrated implementation, the layered file system includes various layers 1802 a-1802 c that are combined with one another to define a file system as known in the art of graph driver plugins for use with DOCKER containers. In the illustrated embodiment, only one layer 1802 a is a read/write (R/W) layer and the remaining layers are read only layers. The R/W layer 1802 a may be configured to mount a remote storage volume 1804 implemented by a storage node 106 according to the methods described herein (see, e.g., FIGS. 1 through 7). As described above, the storage volume 1804 may be a virtualized storage volume that is implemented without the container 1320 having data regarding a storage node 106 or device 108 on which the storage volume is actually stored.

In this manner, any persistent data written or changed by an application instance 1322 executed by the container 1320 will be performed on the remote storage volume 1804. Accordingly, when a snapshot of the container 1320 is made or the container is moved to a different location, the persistent data may be copied or recreated using the remote storage volume. No tracking of changes or other awareness of the persistent state of the application instance 1322 is required in order to achieve this functionality due to the use of the remote storage volume 1804 to implement the R/W layer 1802 a.

FIG. 19 illustrates a method 1900 for using the architecture shown in FIG. 18. The method 1900 may be executed on a compute node 110 or hybrid node. The method 1900 may be executed as part of deployment of a bundled application 1300 in order to create and start a container 1320 on the compute node 110.

The method 1900 may include creating 1902 a container 1320, e.g. a DOCKER container, on the compute node 110 and creating 1904 a layered file system, such as by associating a graph driver plugin with the container 1320. A remote storage volume may also be created 1906, as described above with respect to FIGS. 1 through 7. Creating 1906 a storage volume may be performed by requesting allocation of a storage volume by the storage manager 102.

The method 1900 may include modifying 1908 metadata of the layered file system to refer to the remote storage volume as layer 0 (the R/W layer) of the layered file system.

An instance 1322 of an application executable may be loaded 1910 into the container 1320 as well. The application instance 1322 may be executed 1912, which may result in writing 1914 of persistent date data for the application instance 1322. These writes will be routed by the graph driver plugin to the remote storage volume and persistently stored therein.

If a move instruction is found 1916 to have been received, the method 1900 may include instantiating 1918 a new container at a new location, e.g., a different compute node. The container may be loaded with an instance 1322 of the executable application. The method 1900 may further include mounting 1920 the remote storage volume from step 1906 to the new container as layer 0 of the layered file system. This may include modifying the metadata for the new container as described above with respect step 1908. The state of the application instance 1322 may therefore be created using the data in the remote storage volume.

In some embodiments, the container to be moved may be frozen and copied to the new location, rather than creating a new container. In that case, a clone of the remote storage volume storing the persistent state data may be mounted to create a clone of the container.

The move instruction of step 1916 may be an instruction to move the application instance or be part of a process of cloning the application instance. In either case, execution of the move may be proceeded with creating a snapshot of the application as described above with respect to FIG. 16. Likewise, steps 1918 and 1920 may be executed as part of the rollback process of FIG. 17.

Referring to FIG. 20, a bundled application 1302 may be tested to determine robustness in response to failures. For example, a bundled 1302 may include containers 1320 hosting multiple instances 1322 of individual roles 1312 and various replicas of storage volumes in order to provide a degree of redundancy. Accordingly, the method 2000 may be executed by the orchestration layer 1300 to test the ability of this redundancy to handle faults.

The method 2000 may include specifying 2002 a fault tolerance. This step may be performed manually as a user or developer of a bundled application 1302 specifies a degree of fault tolerance. The fault tolerance may be specified to the orchestration layer 1300 as a number of failures for one or more entity classes, where the entity classes include some or all of storage nodes, compute nodes, containers, application instances, storage server racks, data centers, a network connection or network component (router, switch, network cable, etc.), or any other component of a bundled application 1302 or the distributed computing system on which the bundled application 1302 is executing. For example, the specification may read as follows:

3 compute nodes;

2 storage nodes;

5 containers;

1 rack; and

1 switch.

The method 2000 may further include collecting 2004 statuses of components of an application. The statuses may include statuses of containers 1320, application instances 1322, storage volumes, storage nodes 106, compute nodes 110, and possibly other parts of the distributed computing system, such as network components.

For example, some or all of these components may report their statuses periodically to the orchestration layer 1300 or the orchestration layer may query these components and evaluate response received to determine whether the response includes an error message. The orchestration layer 1300 may interpret a failure to receive a response to a query from a component as a failure. The orchestration layer 1300 may store these statuses, i.e. a listing including a component and its corresponding status for some or all of the components evaluated.

The method 2000 may further include selecting 2006 a fault and selecting 2008 a target for the fault. Selecting 2006 a fault may include selecting an entity class to experience a fault. Selecting a target may include selecting a specific instance of that entity class to experience a fault. Accordingly, if a storage volume is selected, a specific storage volume provisioned for the bundled application may be selected as a target. The selections of steps 2006 and 2008 may be performed randomly, e.g. according to some pseudo random function or using a random number generator as known in the art.

The method 2000 may further include making 2010 a snapshot of the target if possible. For example, if the target is a container, a snapshot of the container may be created (see, e.g. the approach for saving and restoring the state of a container 1320, FIGS. 18 and 19). If the target is a storage volume, then a snapshot of the storage volume may be created (see, e.g. FIG. 2). Where the target is a compute node 110 or hybrid node, then snapshots of the containers 1320 hosted thereon may be created. When the target is a storage node 106 or hybrid node, snapshots of storage volumes implemented thereby may be created.

The method 2000 may include inducing 2012 a fault in the selected target. For example, software implementing a container 1320 or storage volume may include a setting that may be invoked by the orchestration layer to stop it or otherwise cause it to case to perform its function. Likewise, an other element, such as a network component selected as target may be shut down or otherwise instructed to cease functioning. Where a node is selected as the target, then all entities implemented by the node (storage volume and/or container 1320) may be instructed to stop or otherwise cease functioning. The node itself may also be instructed to temporarily cease functioning, such as by ceasing to acknowledge or otherwise process network traffic. Where a rack is selected, then each node of the rack may be processed in a similar manner—hosted storage volume and/or containers 1320 stopped and the node itself instructed to cease functioning. For each storage volume and/or container 1320 that is stopped, snapshots may be created prior to stopping.

The method 2000 may include evaluating 2014 the state of the bundled application 1302. This may include evaluating a status as reported by a component of the application 1302, attempting to access a service implemented by the application 1302, or any other approach known in the art for evaluating the function of an application. For example, where an interface is exposed by the application 1302, the orchestration layer 1300 may access a service implemented by that interface.

If the state of the bundled application 1302 indicates that it is no longer functioning, then the method 2000 may end. A notification may be presented to the user, such as a message indicating circumstances of the test of steps 2006-2012. For example, the notification may include information such as the entity class and target entity and information regarding the state of the application 1302, such as error logs generated by the application 1302.

If the state from step 2014 indicates that the application continues to function, then the method 2000 may include incrementing 2016 a fault count and rolling back 2018 the targets to the snapshots created at step 2010. The fault count may be set to 1 during a first iteration, such that only one target is selected and processed according to steps 2010-2014.

The method 2000 may then continue at step 2004 with the number of faults being equal to the fault count. In particular, steps 2006-2008 may be performed such that N targets are selected, where N is the fault count. For example, N entity class selections may be made randomly made such that the number of times a particular entity class is selected is less than or equal to the number of faults for that entity class specified at step 2002. For the M (M=1 or more) times an entity class is selected, M different targets for that entity class may be randomly selected at step 2008. The method 2000 may then continue repeating at step 2010 with the targets as selected at step 2008.

The method 2000 may continue until one of (a) the application is found to cease to function at step 2014 and (b) the number of faults selected at step 2006 for each entity class is equal to the number specified for each entity class in the fault tolerance. Where condition (b) is met, the application may be determined to meet the fault tolerance and a notification may be transmitted to a user or otherwise recorded that indicates that the fault tolerance of step 2002 is met. In some embodiments, the method 2000 may continue to execute periodically in order to verify that the fault tolerance continues to be satisfied.

Referring to FIG. 21, a node 106, such as a storage node or hybrid node, has a plurality of storage devices 108 a-108 b mounted thereto, the storage devices 108 a-108 b being hard disk drives (HDD), solid state drives (SSD), cloud storage, or some other type of storage device. Each device 108 a-108 b stores one or more storage volumes 2100 a or one or more slices of one or more storage volumes 2100 a, 2100 b, such as according to the approach described herein above. In particular, as described above, slices may be assigned individually to devices 108 a, 108 b such that an entire storage volume 2100 a, 2100 b need not reside on the same device 108 a, 108 b or even devices mounted to the same node 106.

For each device 108 a, 108 b, the node 106 may collect usage statistics. For example, a software component implementing disk virtualization in coordination with the storage manager 102 may track IOPs and usage of the storage volumes 2100 a-2100 b and/or slices of storage volumes 2100 a, 2100 b. In particular, storage usage 2102 may indicate the amount of actual data stored in a storage volume 2100 a, 2100 b or slice of a storage volume 2100 a, 2100 b, such as in the form of a number of allocated segments. IOP usage 2104 may indicate a number of IOPs addressed to a storage volume 2100 a, 2100 b or slice of a storage volume 2100 a, 2100 b. IOP usage may track one or both of write IOPs and read IOPs and may track a total number of IOPs per unit time.

FIG. 22 illustrates a method 2200 for assigning storage volumes to devices 108 a, 108 b of a node 106. The method 2200 may include provisioning 2202 a storage volume 2100 a for use by a bundled application 1302 according to the methods described above. The storage volume 2100 a may then be assigned 2204 to a device 108 a of the node 106. For example, the node 106 may be notified of the assignment and the assignment to the node 106 and device 108 a may be recorded in the volume map 300 for the storage volume 2100 a.

The method 2200 may further include monitoring IOPs 2206 for the storage volume 2100 a and evaluating 2208 whether IOP usage is excessive. In particular, this may include comparing the number of IOPs in a given time window, e.g. 10 ms, 100 ms, 1 second, or the like, to an IOP threshold. If this threshold is exceeded, then the IOPs may be determined 2208 to be excessive. The threshold may be static or dynamic. For example, it may be a function of an average number of IOPs per storage volume assigned to the node 106. The evaluation of step 2208 may evaluate the number of IOPs in the time window for those slices of the storage volume 2100 a assigned to the device 108 a separately from the IOPs for slices assigned to other devices 108 b or nodes.

If the usage is found 2208 to be excessive, then another device may be added 2210 to the storage volume 2100 a and one or more slices of the storage volume may be redistributed 2212. For example, a load balancing approach may be used. The number of IOPs in a time window for the slices of the volume 2100 a may be measured (or past measurements are reused). A first set of slices may be assigned to the first device 108 a and a second set of slices may be assigned to the second device such that the total number of IOPs in the time window for the slices of the first set is approximately equal to the total number of IOPs in the time window for the slices in the second set. “Approximately equal” may mean equal to within a value between the number of IOPs in the time window for the slice with the highest number of IOPs in the time window and the number of IOPs in the time window for the slice with the lowest number of IOPs in the time window.

Steps 2206-2212 may be performed periodically such that IOPs are monitored 2206 for a next time window after (and possibly overlapping) the window used at step 2206 of a previous iteration. Subsequent iterations may result in addition of devices or further redistributing 2212 of slices based on excess usage. In some instances, redistribution 2212 may be performed during an iteration of steps 2206-2212 without adding 2210 a device, such as when neither device 108 a, 108 b is found to be being used within a threshold percentage of its IOPs capacity within the time window of step 2206.

Referring to FIG. 23, the illustrated method 2300 may be performed by the node 106 and/or the orchestration layer 1300 in order to adjust the storage available for a bundled application on the node 106.

The method 2300 may include monitoring 2302 storage usage of the storage volumes hosted by the node 106. For example, storage usage may include counting, by an agent implementing the storage scheme described herein, the number of segments allocated to each storage volume 2100 a, 2100 b and/or slice of each storage volume 2100 a, 2100 b. For example, this information may be obtained from the segment map 314.

The method 2300 may further include estimating 2304 a fill rate for the storage volumes 2100 a, 2100 b on the node 106, which may include the fill rate for the set of slices of a particular storage volume 2100 a, 2100 b on a particular device 108 a, 108 b. The method 2300 may be performed for multiple storage volumes separately (“the subject volume”). In particular, a rate of write IOP generation, segment allocation, or other metric of storage increase per unit time on the node 106 for the subject volume within a predetermined time window may be calculated. The fill rate for the subject volume may be evaluated with respect to some or all of (a) an amount of unused storage in the subject volume, (b) an amount of unused storage in slices of the subject volume assigned to the node 106, (c) an amount of unused storage on an individual device 108 a, 108 b, and (d) a total amount of unused storage on all devices 108 a, 108 b mounted to the storage node 106. Using these values, step 2304 may further include estimating a time until full as one or more of the values of (a)-(d) divided individually by the fill rate.

The method 2300 may include evaluating 2306 whether more storage is needed for the subject node. In particular, if a time until full according to or more of values (a)-(d) is below a threshold time, it may be determined 2306 that more storage is needed for the subject volume.

If no storage is found 2306 to be needed, then the method 2300 may end and be repeated at a later time, such as according to a predefined repetition period.

If more storage is found 2306 to be needed, the method 2300 may further include evaluating 2308 whether more memory, processors, or other computing resources are needed. In particular, high usage of storage may be accompanied by additional requirements for processing, memory, network bandwidth, or other resources.

Accordingly, step 2300 may include evaluating current (e.g., measured during a time window defined for measuring) memory usage, processor usage, network bandwidth usage, NIC usage (network interface controller), rack usage (e.g., number of rack blades in use and amount of use of each blade), or other usage statistic. For example, where the node 106 is a hybrid node, then these statistics may be measured to characterize processing needs of one or more containers hosted by the node 106 and to which the subject volume is mounted. A measured usage value may be compared to a corresponding threshold, which, if exceeded, results in a positive outcome to the evaluation of step 2308.

For example, where step 2308 indicates more processing or memory is needed, the method 2300 may include creating 2310 a new container 1320, provisioning 2312 a new storage volume, and mounting 2314 the new storage volume to the new container 1320. In particular, the new container may be loaded with an instance 1322 of the same application as is accessing the subject volume. In this manner, IOPs may be distributed across multiple containers 1320 and multiple storage volumes thereby resolving the need for more storage and more processors and/or memory. In a like manner, provisioning a new container and storage volume at a different location in a distributed computing system may also eliminate bottlenecks for network traffic determined to be present at step 2308.

Where steps 2310-2314 are executed, the orchestration layer 1300 may notify the bundled application 1302 of the available new container and configure the bundled application 1302 to use the new container, such as by executing a hook 1310 that performs these functions as specified by a developer of the application 1302.

If more storage is found 2306 to be needed but more processing, memory, or other resources are not found 2308 to be needed, the method 2300 may evaluate one or more alternatives to handle the need for additional storage.

For example, the method 2300 may include evaluating 2316 whether expanding of the subject volume, i.e., increasing its size, is possible and desirable. For example, if a device 108 a-108 b has unused storage capacity, the size of the subject volume may be increased 2318 to use up some or all of this capacity, such that the amount of unused storage capacity is above some threshold for excess capacity.

In some embodiments, step 2316 may include evaluating usage of the application's 1302 use of the subject volume. For example, where growth is slow and IOPs are nearly balanced between read and write IOPs, growing of the subject volume may be determined to be a suitable alternative.

If expanding is found 2316 not to be possible, the method 2300 may include evaluating 2320 whether performing garbage collection (GC) on the subject volume would resolve the lack of storage. For example, step 2320 may include evaluating some or all of the following: (a) an elapsed time since GC was performed on the subject volume, (b) an amount of invalid data in the subject volume, (c) and amount of valid data in the subject volume. Determining the amount of valid and invalid data in a slice of a storage volume may be performed as describe above (see description of FIG. 6). Values according to (a) or (c) may be compared to a corresponding threshold condition, which, if met, may invoke performing 2322 GC. For example, if the elapsed time is greater than an elapsed time, then GC may be performed. If the amount of invalid data is above an invalid data threshold, GC may be performed in some embodiments. If the amount of valid data is below a valid data threshold, GC may be performed in some embodiments.

The method 2300 may further include evaluating 2324 whether adding a disk is needed. In some embodiments, if neither of steps 2316-2320 are found to indicate other options for increasing storage, adding 2324 of a disk is found 2324 to be needed. In other cases, additional considerations may be evaluated at step 2324, such as whether an additional disk is mounted to the node 106 or is available for mounting to the node, such as based on an inventory or topology of a network as provided to the node 106 or orchestration layer. If addition of a disk to the subject volume is determined 2324 to be possible and desirable, the method 2300 may include adding 2326 an additional disk to the subject volume and redistributing 2328 slices of the subject volume, such as in the manner described for steps 2210 and 2212 of the method 2200.

The method 2300 may be repeated periodically in order to accommodate changes in usage.

Referring to FIG. 24, In some embodiments, the node 106 may additionally maintain a volume limit 2400 a, 2400 b for each device 108 a, 108 b that specifies the number of storage volumes 23100 a-2100 c that may be allocated to that device 108 a, 108 b. The limit may be specified as a number of volumes, a number of slices, a maximum quantity of storage represented by allocated storage volumes (GB, TB, etc.). The limits 2400 a, 2400 b may be set initially by the orchestration layer 1300 and may subsequently be adjusted by logic executing on the node 106 or orchestration layer 1300 as described with respect to FIG. 25.

FIG. 25 illustrates a method 2500 for adjusting the volume limit for devices 108 a, 108 b of a node 106 and which may be executed by the node 106 and/or orchestration layer 1300.

The method 2500 may include setting 2502 an initial volume limit. This may be a system-wide default implemented by the orchestration layer 1300 or an application-wide limit specified by the bundled application 1302. The volume limit may be specified by a bundled application 1302 for each role 1312. The volume limit may be distributed by the orchestration layer 1300 to the nodes 106 to which storage devices 108 a, 108 b are mounted.

The method 2500 may further include monitoring 2504 throughput (IOPs) of the storage volumes 2100 a, 2100 b or slices of these volumes. In particular, the number of IOPs per unit time (e.g., per 10 ms, 100 ms, 1 second, or other period) may be measured periodically. Read and write IOPs may be counted separately or aggregated.

The method 2500 may further include evaluating 2506 whether there is a throughput imbalance on the device 108 a, 108 b of the node 106. Evaluating throughput may include evaluating read and write IOPs and may also include evaluating IOPs from performing garbage collection (GC), replication, or other sources of IOPs. For example, if the aggregate throughput of the volumes or slices of volumes on a device 108 a, 108 b may be determined to be imbalanced based on one or more of the following criteria:

-   -   1. The aggregate throughput is above a predetermined upper         threshold for the device 108 a, 108 b.     -   2. The aggregate throughput is below a predetermined lower         threshold for the device 108 a, 108 b.     -   3. The aggregate throughput of a first device 108 a, 108 b is         above the throughput of a second device 108 b, 108 a of the node         by some relative amount, e.g. T1 is greater than X*T2, where T1         is the throughput of the first device, T2 is the throughput of         the second device, and X is a value greater than 1.     -   4. The aggregate throughput of a first device 108 a, 108 b is         above the throughput of a second device 108 b, 108 a of the node         by some relative amount, e.g. T1 is greater than Y+T2, where T1         is the throughput of the first device, T2 is the throughput of         the second device, and Y is a predetermined number of IOPs per         unit time.

If an imbalance is found 2506, the method 2500 may include reducing 2508 the volume limit for the device 108 a, 108 b having high throughput according to conditions 1, 3, or 4, above. For example, if the volume limit is 10, only two volumes (or some number of slices of volumes) have been assigned to device 108 a, and its throughput is high enough to meet one of the conditions 1, 3, or 4, the volume limit for device 108 a may be reduced, such as to a limit of two.

If an imbalance is found, the method 2500 may further include augmenting 2510 the volume limit for a device 108 a, 108 b that has low throughput according to condition 2 or is the second device where a first device meets condition 3 or 4. For example, a device 108 b that has a number of volumes assigned thereto meeting the volume limit may have its volume limit increased to permit the assignment of more storage volumes or slices inasmuch as its throughput is low.

Note that in some instances only step 2508 is executed where an imbalance found 2506. In other instances, both of steps 2508 a and 2510 are executed. In still others only step 2510 is performed. For example, if condition 1 is met, only step 2508 is performed in some embodiments. If condition 2 is met, only step 2510 is performed in some embodiments.

The method 2500 may further include evaluating 2512 whether a new device has been added to the node 106. In that case, the method 2500 may include rebalancing volume limits according to usage. For example, the volume limit of a first device having higher throughput relative to a second device of the node may be reduced in response to addition of a third device such that additional volumes will be assigned to the third device. Where the rebalancing of the load limits causes the volume limit of the first device to be less than the number of volumes assigned to it, one or more volumes assigned to the first device may be transferred to the third device. This transfer may be based on usage. For example, volumes may be transferred to the third device based on throughput with the lowest throughput volumes being transferred until the volume limit is met on the first device.

In the event that a new storage volume is found 2514 to be added to the node 106, the storage volume maybe assigned 2516 to a device based on the current load limits as adjusted according to any of the foregoing steps and throughput of the devices. For example, the new volume may be assigned to the device having the lowest throughput of those devices having volumes assigned thereto under their volume limits.

FIG. 26 is a block diagram illustrating an example computing device 2600. Computing device 2600 may be used to perform various procedures, such as those discussed herein. The storage manager 102, storage nodes 106, compute nodes 110, and hybrid nodes, may have some or all of the attributes of the computing device 2600.

Computing device 2600 includes one or more processor(s) 2602, one or more memory device(s) 2604, one or more interface(s) 2606, one or more mass storage device(s) 2608, one or more Input/output (I/O) device(s) 2610, and a display device 2630 all of which are coupled to a bus 2612. Processor(s) 2602 include one or more processors or controllers that execute instructions stored in memory device(s) 2604 and/or mass storage device(s) 2608. Processor(s) 2602 may also include various types of computer-readable media, such as cache memory.

Memory device(s) 2604 include various computer-readable media, such as volatile memory (e.g., random access memory (RAM) 2614) and/or nonvolatile memory (e.g., read-only memory (ROM) 2616). Memory device(s) 2604 may also include rewritable ROM, such as Flash memory.

Mass storage device(s) 2608 include various computer readable media, such as magnetic tapes, magnetic disks, optical disks, solid-state memory (e.g., Flash memory), and so forth. As shown in FIG. 26, a particular mass storage device is a hard disk drive 2624. Various drives may also be included in mass storage device(s) 2608 to enable reading from and/or writing to the various computer readable media. Mass storage device(s) 2608 include removable media 2626 and/or non-removable media.

I/O device(s) 2610 include various devices that allow data and/or other information to be input to or retrieved from computing device 2600. Example I/O device(s) 2610 include cursor control devices, keyboards, keypads, microphones, monitors or other display devices, speakers, printers, network interface cards, modems, lenses, CCDs or other image capture devices, and the like.

Display device 2630 includes any type of device capable of displaying information to one or more users of computing device 2600. Examples of display device 2630 include a monitor, display terminal, video projection device, and the like.

Interface(s) 2606 include various interfaces that allow computing device 2600 to interact with other systems, devices, or computing environments. Example interface(s) 2606 include any number of different network interfaces 2620, such as interfaces to local area networks (LANs), wide area networks (WANs), wireless networks, and the Internet. Other interface(s) include user interface 2618 and peripheral device interface 2622. The interface(s) 2606 may also include one or more peripheral interfaces such as interfaces for printers, pointing devices (mice, track pad, etc.), keyboards, and the like.

Bus 2612 allows processor(s) 2602, memory device(s) 2604, interface(s) 2606, mass storage device(s) 2608, I/O device(s) 2610, and display device 2630 to communicate with one another, as well as other devices or components coupled to bus 2612. Bus 2612 represents one or more of several types of bus structures, such as a system bus, PCI bus, IEEE 1394 bus, USB bus, and so forth.

For purposes of illustration, programs and other executable program components are shown herein as discrete blocks, although it is understood that such programs and components may reside at various times in different storage components of computing device 2600, and are executed by processor(s) 2602. Alternatively, the systems and procedures described herein can be implemented in hardware, or a combination of hardware, software, and/or firmware. For example, one or more application specific integrated circuits (ASICs) can be programmed to carry out one or more of the systems and procedures described herein.

In the above disclosure, reference has been made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific implementations in which the disclosure may be practiced. It is understood that other implementations may be utilized and structural changes may be made without departing from the scope of the present disclosure. References in the specification to “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

Implementations of the systems, devices, and methods disclosed herein may comprise or utilize a special purpose or general-purpose computer including computer hardware, such as, for example, one or more processors and system memory, as discussed herein. Implementations within the scope of the present disclosure may also include physical and other computer-readable media for carrying or storing computer-executable instructions and/or data structures. Such computer-readable media can be any available media that can be accessed by a general purpose or special purpose computer system. Computer-readable media that store computer-executable instructions are computer storage media (devices). Computer-readable media that carry computer-executable instructions are transmission media. Thus, by way of example, and not limitation, implementations of the disclosure can comprise at least two distinctly different kinds of computer-readable media: computer storage media (devices) and transmission media.

Computer storage media (devices) includes RAM, ROM, EEPROM, CD-ROM, solid state drives (“SSDs”) (e.g., based on RAM), Flash memory, phase-change memory (“PCM”), other types of memory, other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store desired program code means in the form of computer-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer.

An implementation of the devices, systems, and methods disclosed herein may communicate over a computer network. A “network” is defined as one or more data links that enable the transport of electronic data between computer systems and/or modules and/or other electronic devices. When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or a combination of hardwired or wireless) to a computer, the computer properly views the connection as a transmission medium. Transmissions media can include a network and/or data links, which can be used to carry desired program code means in the form of computer-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer. Combinations of the above should also be included within the scope of computer-readable media.

Computer-executable instructions comprise, for example, instructions and data which, when executed at a processor, cause a general purpose computer, special purpose computer, or special purpose processing device to perform a certain function or group of functions. The computer executable instructions may be, for example, binaries, intermediate format instructions such as assembly language, or even source code. Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the described features or acts described above. Rather, the described features and acts are disclosed as example forms of implementing the claims.

Those skilled in the art will appreciate that the disclosure may be practiced in network computing environments with many types of computer system configurations, including, an in-dash vehicle computer, personal computers, desktop computers, laptop computers, message processors, hand-held devices, multi-processor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframe computers, mobile telephones, PDAs, tablets, pagers, routers, switches, various storage devices, and the like. The disclosure may also be practiced in distributed system environments where local and remote computer systems, which are linked (either by hardwired data links, wireless data links, or by a combination of hardwired and wireless data links) through a network, both perform tasks. In a distributed system environment, program modules may be located in both local and remote memory storage devices.

Further, where appropriate, functions described herein can be performed in one or more of: hardware, software, firmware, digital components, or analog components. For example, one or more application specific integrated circuits (ASICs) can be programmed to carry out one or more of the systems and procedures described herein. Certain terms are used throughout the description and claims to refer to particular system components. As one skilled in the art will appreciate, components may be referred to by different names. This document does not intend to distinguish between components that differ in name, but not function.

It should be noted that the sensor embodiments discussed above may comprise computer hardware, software, firmware, or any combination thereof to perform at least a portion of their functions. For example, a sensor may include computer code configured to be executed in one or more processors, and may include hardware logic/electrical circuitry controlled by the computer code. These example devices are provided herein purposes of illustration, and are not intended to be limiting. Embodiments of the present disclosure may be implemented in further types of devices, as would be known to persons skilled in the relevant art(s).

At least some embodiments of the disclosure have been directed to computer program products comprising such logic (e.g., in the form of software) stored on any computer useable medium. Such software, when executed in one or more data processing devices, causes a device to operate as described herein.

While various embodiments of the present disclosure have been described above, it should be understood that they have been presented by way of example only, and not limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the disclosure. Thus, the breadth and scope of the present disclosure should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents. The foregoing description has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. Further, it should be noted that any or all of the aforementioned alternate implementations may be used in any combination desired to form additional hybrid implementations of the disclosure. 

The invention claimed is:
 1. A method comprising: providing a plurality of computing devices including a first computing device; providing a plurality of containers executing on the plurality of computing devices, the plurality of containers implementing roles of a bundled application; providing a plurality of storage devices mounted to the plurality of computing devices and storing a plurality of storage volumes; receiving, by the first computing device, a fault tolerance specification; and iteratively inducing, by the first computing device, simulated failure in a number of selected entities from among a plurality of entities including the plurality of containers and the plurality of storage volumes with the number of selected entities increasing with each iteration until one of (a) the bundled application ceases to function and (b) the number of selected entities meets the fault tolerance specification; wherein the fault tolerance specification specifies, for each class of entity of a plurality of entity classes, a number of fault for the each class; wherein the plurality of entity classes include a container class and a storage volume class; and wherein the method further comprises, for each iteration, selecting the selected entities such that, for each class of entity, the number of the selected entities belonging to the each class is less than or equal to the number of faults for the each class.
 2. The method of claim 1, further comprising restoring functioning of the selected entities following each iteration.
 3. The method of claim 2, further comprising creating snapshots of the selected entities prior to inducing failure for each iteration.
 4. The method of claim 3, wherein restoring functioning of the selected entities following each iteration comprises restoring the selected entities from the snapshots.
 5. The method of claim 1, wherein the bundled application includes at least one of CASSANDRA, HADOOP, SPARK, DRUID, SQL database, ORACLE database, MONGODB database, and WORDPRESS.
 6. The method of claim 1, wherein the bundled application is a HADOOP application and the plurality of containers executing roles of the HADOOP application including a name node, data node, zookeeper, and AMBARI server.
 7. The method of claim 1, further comprising: receiving, by the first computing device, a manifest for the bundled application; provisioning, by the first computing device, the plurality of containers and the plurality of storage volumes according to the manifest.
 8. A system comprising: a plurality of computing devices including a first computing device; a plurality of containers executing on the plurality of computing devices, the plurality of containers implementing roles of a bundled application; and a plurality of storage devices mounted to the plurality of computing devices and storing a plurality of storage volumes; wherein the first computing device is programmed to: receive a fault tolerance specification; and iteratively induce simulated failure in a number of selected entities from among a plurality of entities including the plurality of containers and the plurality of storage volumes with the number of selected entities increasing with each iteration until one of (a) the bundled application ceases to function and (b) the number of selected entities meets the fault tolerance specification; wherein the first computing device is programmed to invoke restoring of functioning of the selected entities following each iteration; wherein the first computing device is programmed to invoke creation of snapshots of the selected entities prior to inducing failure for each iteration.
 9. The system of claim 8, wherein the first computing device is programmed to invoke restoring functioning of the selected entities following each iteration by restoring the selected entities from the snapshots.
 10. The system of claim 8, wherein the fault tolerance specification specifies, for each class of entity of a plurality of entity classes, a number of faults for the each class.
 11. The system of claim 10, wherein the first computing device is programmed to, for each iteration, select the selected entities such that, for each class of entity, the number of the selected entities belonging to the each class is less than or equal to the number of faults for the each class.
 12. The system of claim 11, wherein the plurality of entity classes include a container class and a storage volume class.
 13. The system of claim 8, wherein the bundled application includes at least one of CASSANDRA, HADOOP, SPARK, DRUID, SQL database, ORACLE database, MONGODB database, and WORDPRESS.
 14. The system of claim 8, wherein the bundled application is a HADOOP application and the plurality of containers executing roles of the HADOOP application including a name node, data node, zookeeper, and AMBARI server.
 15. The system of claim 8, wherein the first computing device is programmed to: receive a manifest for the bundled application; and provision the plurality of containers and the plurality of storage volumes according to the manifest.
 16. A system comprising: a plurality of computing devices including a first computing device; a plurality of containers executing on the plurality of computing devices, the plurality of containers implementing roles of a bundled application; and a plurality of storage devices mounted to the plurality of computing devices and storing a plurality of storage volumes; wherein the first computing device is programmed to: receive a fault tolerance specification; and select a number of failures; perform a test method including: after selecting the number of failures, randomly selecting selected entities from among a plurality of entities including the plurality of containers and the plurality of storage volumes, a number of the selected entities being equal to the number of failures; after selecting the selected entities, inducing simulated failure of the selected entities; and after inducing simulated failure of the selected entities, evaluating whether the bundled application has ceased to function as a result of the simulated failure of the selected entities; and repeat the test method such that the number of failures is increased with each iteration until one of (a) the bundled application ceases to function in an iteration of the test method and (b) the number of failures of the iteration of the test method meets the fault tolerance specification.
 17. The system of claim 16, wherein the fault tolerance specification specifies, for each class of entity of a plurality of entity classes, a number of faults for the each class; and wherein the test method further comprises, for each iteration, selecting the selected entities such that, for each class of entity, the number of the selected entities belonging to the each class is less than or equal to the number of faults for the each class. 